Temperature responsive electric switch



July 28, 1959 --r 2,897,320

TEMPERATURE RESPONSIVE E LECTRIC SWITCH Filed April 50, 1958 United States Patent RESPONSIVE ELECTRIC SWITCH Fred D. Patti, Morris, Ill.

Application April 30, 1958, Serial No. 731,906

10 Claims. (Cl. 200138) The present invention relates to a temperature responsive electric switch wherein one of the contact members is positioned in an 011? position or a selected on position under control of a manual adjustment member and the second contact member is movable relative to said other contact member under control of a thermally responsive actuator to maintain said second contact member in on or off positions relative to .the other contact member when the latter is in on position.

In switches of this type it is desirable to provide means for controlling the position of the second contact member to prevent its reengagement with the other contact member when the latter is in o position.

With this in view, it is an object of this invention to provide a switch of the character indicated in which stop means of novel construction and arrangement are providedfor cooperation with the contact member associated with the thermally responsive actuator to positively position said contact member in a selected off position while the other contact member is in off position under control of the manual adjustment member.

It is a further object of this invention to provide such stop means embodying features which make it susceptible to simple and economical manufacturing procedure as well as to assure effective and accurate control of operations to which a switch of the character indicated is applied in actual use.

Additional features and .advantages of this invention will become apparent as the following description proceeds and the features of novelty which characterize this invention will be set forth in the claims .appended to and forming a part of this specification.

'For a more complete understanding of this invention reference should be had to the accompanying drawings in which:

Fig. l is a top plan view of a temperature responsive electric switch embodying the features of this invention.

Fig. 2 is a side elevational view thereof showing the contact members in on position while the actuator has travelled to aposition out of engagement with said contact member otherwise controlled by said actuator.

Pig. 3 is a similar view showing the contact member with which the manual adjustment member cooperates n on position as in Fig. '2 but showing the-other contact member in off position under control of the actuator.

'Fig. 4 is a fragmentary section taken along line 4-4 of Fig. 2 showing the stop means partly in elevation.

Fig. 5 is a fragmentary side elevational view showing the manual adjustment member and its cooperating contact member in off position while showing the other contact member in engagement with the stop to obstruct further movement of the latter contact member in the direction of the actuator.

Reference being had more particularlyto the drawings, there --is shown a switch representing .a preferred .embodiment "of this invention which includes a rigid supporting member or strip and a pair of elongated resilient metal contact blades comprising a first contact blade 11 and a second contact blade 12. Reference numeral 13 designates a hollow fastener or rivet secured to and projecting angularly from one end of the supporting member 10 on which the blades 11 and 12 are arranged and supported in superposed aligned relation with the supporting member 10 and the blade 12 instrad dling relation to the blade 11. An insulating spacer 14 separates the blade 11 from a wiring terminal .15 on the rivet 13 'with which terminal the blade 12 has conductive engagement at the surface of the blade 12 facing the blade 11. A second wiring terminal 16 with which the blade 11 has conductive engagement is separated from the support 10 by a second insulating spacer 17. Reference numeral 18 designates an elongated thermally responsive actuator blade supported on the rivet 13 .between an insulating spacer 19 and a head extending from the end of the rivet 13 opposite .to the end thereof secured to the support 10. Thus the wiring terminals 15 and 16, and .the insulating spacers 17, 14 and 19 combine with the support 10 to provide stacking means for clamping the blades 11, -12 and 18 about the post 13 in alignment with the support 10, with the blades 11 and 18 in straddling relation to the blade 12. It will be noted that blades 11 and 18 are longer than blade 12 wherebylan insulating button 20 fastened to the free end of the blade .18 is :in a position :to clear the end-of blade 12 for engagement with the surface of the blade 11 :facing said button 20. Upon .defiection of the blade 18 in response to .a predetermined temperature condition so as to cause the button 20 to move'the blade 11 in a direction away from the blade 12, while the blade .12

is in on position as shown in .Fig. 3,, a contact button 7 21 on blade 12 is freed of engagement-bya similar con tact button 22 on the blade 11 whereby the circuit through said contact buttons 21 and 22 .is broken. Upon subsequent predetermined variation of the temperature in accordance with whichtheblade 18 responds :by movement inadirection-away from the blade 11, as shown in Fig. 2, .the blade 11 .in response to inherent stresses urging said blade 11 toward the insulating button 20 will travel with .the blade v18 until the contact 22 reengages contact .21 on blade 12 to .close the circuit .throughsaid contacts avhile .the contactblade 12 is in on position.

A nut 23 fastened 'throughan opening in the mounting plate 10 :at a suitable distance from the rivet 13 in the direction of the unfastened ends of the .contact blades is provided with a threaded adjustment shaft 24 which forms a manual adjustment member rotatably mounted in said bearing for relative axial movement between retracted and advanced positions ina pathextending into the area between the mounting .01 support member 10 and the blade 11. An insulating tip 25 :secured .to the leading end portion of the shaft 24 and having entryto the space between the contact blades 11 and 12 svia an opening in the contact blade '11;so as to enable the blade 12 to have engagement with said tip 25, isaccordingly movable for adjustment between a retracted and a selected advanced position in response to rotation of the shaft 24. The :resilient bias of the contact blade 12 urges theilatter toward aiposition in .engagement'with the insulating tip 25. Thus by operationof-the:adjustment shaft .24 the "blade 12 :is positioned in a selected retracted position to set the blade 1 2 in an operating or'on position, as exemplified in Figs. 2 and 3, orpositioned in an'advanced position to set the blade12 in an olf position as shown in Fig. 5.

When the switch is in off position as determinedby the arrangement of the blade 12in o position under control. of the adjustment shaft 24, it 'istdes'irahle to positively limit the travel of the contact blade 11in the direction of the contact blade 12 under temperature conditions wherein the actuator 18 is so affected as to be deflected in a direction away from the blade 11 a distance suflicient to allow reengagement of the contacts 22 and 21. To this end, such displacement of the blade 11 is controlled within a predetermined range by means of a stop secured to the support at such a distance from the adjustment shaft and the rivet 13 as to have engagement with the portion of the blade 11 reaching beyond the area of said blade engaged by the actuator button 20. This stop includes a shank portion 28 having threaded connection to the support 10 and an opening in the blade 11 through which the shank has entry to the area between the blade 11 and the blade 12. Edge portions of the opening in the blade 11 facing the blade 12 have engagement with a shoulder 29 at the end of the shank portion 28 to positively obstruct travel of the blade 11 in the direction of the blade 12, according to the predetermined position of the shank portion 28 relative to the mounting support 10. A slot 30 at the shouldered end of the shank portion 28 as well as a slot 31 at the opposite end of the shank portion 28 make it possible, with the aid of a screw driver or the like, to utilize either slot 30 or slot 31 to turn the shank portion 28 to selected adjusted positions according to the desired position of the shoplder relative to the portion of the blade 11 having engagement with said shoulder.

Consequently, the contacts 21 and 22 are maintained in separated relation when the shaft 24 is rotated to place the contact blade 12 in off position, as shown in Fig. 5, even though actuator blade 18 relaxes sufficiently to locate the insulating button 20 thereon in a position to clear the path of the blade 11 to a position wherein its contacts 22 has engagement with contact 21 on blade 12.

The present invention, by thus providing an adjustable stop with which the blade 11 has positive engagement at its outer end portion rather than its fastened end, makes greater precision of adjustment possible for any selected setting between the limits of a desired operating range. It is also clear that the present invention provides a thermal switch of such design and construction as to be simple and convenient to manufacture and install and which is effective and accurate in its control operations under a wide range of conditions, and which possesses wide adaptability to a variety of actual service conditions.

While the prment invention has been shown and described in a specific embodiment thereof, it is clear that modifications may occur to those skilled in the art and it is therefore intended to cover in the appended claims all modifications that are within the true spirit and scope of this invention.

What is claimed is:

1. A temperature responsive electric switch having a pair of elongated contact blades including a first contact blade and a second contact blade, an elongated thermally responsive actuator blade, a rigid support having a first portion on which said blades are fastened at one end thereof in stacked aligned relation with the first blade and said actuator blade in straddling relation to said second blade and said support and said second blade in straddling relation to said first blade, said support having a second and third portion arranged progressively away from said first portion, a manually adjustable member mounted on said second portion of the support with which the second blade cooperates to set the position of the latter between a selected retracted on position and an advanced off position, said actuator blade being operative in response to a predetermined variation from a selected operating temperature to position the first blade between circuit opening and circuit closing positions when said second blade is in on position, and means obstructing movement of said first blade to on position when said second blade is in off position ineluding a stop projecting from said third portion of the support with which the first blade is engageable.

2. A temperature responsive electric switch according to claim 1 wherein said stop has adjustable connection to said support.

3. A temperature responsive electric switch according to claim 1 wherein said stop includes a shank having threaded connection with said support and a shoulder on said shank presents a surface facing said support with which the first blade is engageable.

4. A temperature responsive electric switch according to claim 1 wherein said stop includes a shank having threaded connection with said support and has entry to the area between said first and second contact blades and a shoulder on the portion of the shank in said area is engaged by said first contact blade.

5. A temperature responsive electric switch according to claim 4 wherein said shank has entry to the area between said first and second contact blades via an opening in said first blade, and a shoulder on the portion of the shank in said area is engaged by said blade along the surface defining said opening.

6. A temperature responsive electric switch according to claim 1 wherein said actuator and said first blade have engagement via an insulating member carried by said actuator blade, and such engagement is confined to an area at less distance from the fastened end of the first blade than the distance from the first to the third portion of said support.

7. A temperature responsive electric switch having a pair of elongated contact blades including a first contact 'blade and a second contact blade, an elongated thermally responsive actuator blade, a rigid support having a first portion on which said blades are fastened at one end thereof in stacked aligned relation with the first blade and said actuator blade in straddling relation to said second blade and said support and said second blade in straddling relation to said first blade, said support having a sec end portion, a manually adjustable member mounted on said second portion of the support with which the second blade cooperates to set the position of the latter be tween a selected retracted on position and an advanced off position, said actuator blade being opeartive in response to a predetermined variation from a selected op erating temperature to position the first blade between circuit opening and circuit closing positions when said second blade is in on position, and means obstructing movement of said first blade to on position when said second blade is in off position including a stop on said support at a location remote from said first and second portions with which stop said first blade is engageable.

8. A temperature responsive electric switch according to claim 7 wherein said stop has adjustable connection to said support.

9. A temperature responsive electric switch according to claim 7 wherein said stop has adjustable connection to said support and said stop includes a shank having a shoulder at the end thereof remote from said support with which shoulder the first blade is engageable.

10. A temperature responsive electric switch according to claim 7 wherein said stop has threaded connec tion to said support and said stop includes a shank having a shoulder at the end thereof remote from said support with which shoulder the first blade is engageable, said stop having a slot at the end thereof facing in one direction from said support and a second slot at the end thereof facing in the opposite direction from said support.

References Cited in the file of this patent UNITED STATES PATENTS 2,317,033 Dalforn Apr. 20, 1943 2,518,595 Bletz Aug. 15, 1950 

